This invention relates to a method for separating a recording paper from an image retaining member in which electrostatic forces between the image retaining member and the recording paper may be eliminated or reduced by means of a.c. corona discharge for separation of the recording paper from the image retaining member, and to an apparatus therefor.
In an electrostatic apparatus such as an electrophotographic copier, a copy paper must be separated from an image retaining member after a visible toner image is transferred from the latter to the former. For the above copy paper separation, various methods have been proposed and put into practical use. For example, a pneumatic method making use of an air jet, a mechanical method making use of a belt or claw, and an electrostatic method by which attractive forces between the image retaining member and copy paper are removed under a.c. or d.c. charging to the reverse polarity of neutralization for paper separation. Though these methods have their own merits and demerits, the electrostatic method making use of a.c. corona discharge is most often adapted from the total point of view. The reason is because the image can be transferred to the whole page of copy paper without soiling such paper, and the image retaining member such as a photoconductor is free from damage such as scratches.
However, the electrostatic method of copy paper separation causes some problems. Namely, the separation performance of the electrostatic method depends on the type of copy image and is inferior in degree of reliable performance of separation when compared to the mechanical method making use of a belt.